The diagram shows the elements in the alkali group.
Why do these elements have similar chemical properties?
A. They are all metals.
B. They are all non-metals.
C. They have the same number of electrons
D. They have the same number of valence electrons.
D. They have the same number of valence electrons.
D. They have the same number of valence electrons.
The elements in the alkali group have similar chemical properties because they all have the same number of valence electrons. Valence electrons are the electrons in the outermost shell of an atom and are responsible for the atom's chemical behavior. In the alkali group, all the elements have one valence electron, which makes them highly reactive and likely to lose that electron to form a positively charged ion. This similarity in the number of valence electrons leads to similar chemical properties among the alkali group elements.
The correct choice is D. They have the same number of valence electrons.
The alkali group, also known as Group 1 or Group IA, consists of elements such as lithium (Li), sodium (Na), potassium (K), and so on. These elements have similar chemical properties primarily because they all have the same number of valence electrons, which is 1. Valence electrons are the electrons present in the outermost energy level of an atom.
Having the same number of valence electrons means that these elements have similar electronic configurations and are likely to exhibit similar chemical behaviors. They tend to lose one electron, forming a positive 1 charge (cation) to achieve a stable electron configuration similar to the noble gas in the previous period (helium for Group 1). This electron loss makes them highly reactive in chemical reactions, particularly with nonmetals that readily accept electrons to form compounds.
Option A, "They are all metals," is not correct because although alkali elements are typically metals, not all metals have similar chemical properties.
Option B, "They are all non-metals," is incorrect as well because alkali elements are indeed metals, not non-metals.
Option C, "They have the same number of electrons," is incorrect because while alkali elements may have different numbers of total electrons, they do have the same number of valence electrons, which determines their chemical behavior.